288 PovaH: A CRITICAL STUDY OF 
varians, M. aromaticus, M. griseosporus, M. coprophilus, and M, 
griseo-lilacinus. 
As has been mentioned before, it was decided to use bread as 
a standard medium for the comparative study of the species of 
Mucor. A convenient and, at the same time, uniform style of 
culture was a further desideratum. The tall lipless beakers de- 
scribed in the method of making herbarium preparations proved 
unsuitable in this case, by reason of their large size, and the im- 
possibility of opening them after they had stood for some time 
without contaminating the culture. This was doubtless due to the 
fact that the cotton used to make the (Petri dish) cover tight served 
as a collector of spore-containing dust. After several arrange- 
ments, the following method was evolved, and this has proved 
successful and easy of manipulation. Two glass capsules, each 
containing about I c.c. of bread (fresh bread, slightly moistened, 
or dried bread with sufficient water added to form a paste after 
autoclaving), were placed side by side in a 125 mm. crystallizing 
dish. This was covered first with a thin layer of cotton batting, 
and then with a circular glass plate about 12.5 cm. in diameter. 
These preparations were autoclaved three or four hours at fifteen 
pounds pressure. All of the descriptions and figures, unless 
otherwise specified, were made from cultures prepared according 
to the above-described method. The height in each case was 
checked by comparison with herbarium cultures in the tall beakers. 
The author assumes that anyone attempting to identify a 
mucor has found some difficulty with the already existing keys, in - 
that it is necessary first of all to determine whether or not the 
sporangiophores are branched or simple, and if the former, whether 
racemosely or cymosely branched. To facilitate matters, con- 
sideration will first be given to the question of simple and branched 
sporangiophores. Lendner gives as a parenthetical expression 
after his unbranched group ‘exceptionally, when the conditions 
of nutrition are unfavorable, branches are formed; they are cases 
of anomaly.’”’ This immediately causes trouble, because if 
branching is found in a species it must be determined whether it is 
anomalous or not. To give a concrete example, Wehmer (1903) 
described a mucor under the name Mucor hiemalis as ‘‘ mostly 
unbranched (seldom with lateral branches),’’ and this has been 
